I've got a '95 Montero LS 3.0L with about 200,000 miles on it. It's got decent (equal-ish) compression in all cylinders. I bought it pretty cheap ($1,000) and had a mechanic put more than that amount of money into replacing and repairing things.
After working on it for a while, he's got most of the "bugs" ironed out except for one.
When the truck is running and up to temp, the engine starts "popping", making a backfiring sound about every 8-10 seconds at idle. My mechanic thinks that the engine is getting too much fuel and that is causing it to "pop". He hasn't been able troubleshoot the reason why. He pulled the new catalytic converter out of concern that the "popping" or excess fuel will damage the cat, but he can't figure out how to make the engine run properly.
The Montero has got brand new spark plugs and wires. A basic tune-up didn't fix anything. Anyone have any troubleshooting ideas I can pass on to my mechanic?
I really appreciate your insight and the advice posted in this forum. I can't wait to actually DRIVE this truck, but it's got to be running right before it can pass WA emissions and get licensed!